State what the copper must do
Separate signal reference, power return, shielding, heat spreading, and incidental copper balance. One layer may serve several functions, but each needs a named requirement. Start with controlled-impedance planning when critical signals depend on the plane. A grounded copper area is not automatically an adequate reference for every route above it.
Plane decision matrix
| Review item | Design question | Evidence or action |
|---|---|---|
| Signal reference | Which routes depend on continuous nearby copper? | Review channel geometry including transitions |
| Return current | Where does each load close its circuit? | Map connections through terminals and branches |
| Shield connection | How is the shield connected to its reference? | Specify joints and termination geometry |
| Motion | Which region changes shape? | Evaluate the actual patterned construction |
Compare patterns using the actual routes
If a hatched pattern is proposed, examine where each signal lies relative to openings and how return connections continue across the region. Check the transition to solid copper and any shielding connection. Coordinate with motion design because a pattern may change local stiffness as well as electrical behavior. Avoid choosing a hatch percentage without a specific review objective.
Validate the selected compromise
Document the final pattern, orientation, layer spacing, and allowed variations. Recalculate or test the relevant electrical behavior using the geometry that will be fabricated. Include the same copper pattern in mechanical samples. Comparing a solid-plane electrical coupon with a differently patterned moving assembly can leave the most important interaction untested.
Before you release the design
- List every intended plane function before removing copper.
- Inspect reference continuity under each critical route.
- Keep the manufactured pattern in the stackup and drawing records.
- Review electrical and mechanical evidence after pattern changes.
Watch points
- A hatched plane is not an automatic substitute for a solid reference.
- Do not infer an impedance target from a copper-coverage percentage.
Practical questions
Is a hatched ground always better for bending?
No universal choice follows from the word hatched. Pattern, stackup, motion, and electrical requirements must be evaluated together in the actual assembly.
Can I remove the plane only in the bend?
It is a candidate construction change. Review return continuity, channel transitions, shielding, and the new mechanical boundaries before accepting it.
Technical references
References support the material or design context. Check the exact grade, part number, document revision and project conditions before release.Updated 27 September 2026 · Technical content policy · Engineering guidance supports project review; the agreed drawing defines the build.